LOCATION ORFORD OREstablished Series
TAXONOMIC CLASS: Fine, isotic, mesic Typic Palehumults
TYPICAL PEDON: Orford gravelly silt loam-forested, on a northeast-facing slope of 16 percent at an elevation of 1100 feet. (Colors are for moist soil unless otherwise stated.)
Oi--0 to 2 inches; duff layer of partially decomposed leaves, twigs and needles.
A1--2 to 7 inches; very dark grayish brown (10YR 3/2) gravelly silt loam, brown (10YR 5/3) dry; moderate fine and medium granular structure; soft, very friable, slightly sticky and slightly plastic; many very fine and fine, and common medium roots; many very fine and fine irregular pores; 25 percent 2 to 10 millimeters gravel; strongly acid (pH 5.2); clear smooth boundary. (2 to 11 inches thick)
A2--7 to 14 inches; dark brown (7.5YR 3/4) gravelly silt loam, yellowish brown (10YR 5/4) dry; moderate fine and medium subangular blocky structure parting to fine and medium granular; slightly hard, friable, slightly sticky and slightly plastic; common very fine and fine roots; many very fine and fine irregular pores; 20 percent 2 to 10 millimeters gravel; strongly acid (pH 5.2); clear smooth boundary. (0 to 10 inches thick)
BA--14 to 24 inches; dark brown (7.5YR 3/4) silty clay loam, yellowish brown (10YR 5/4) dry; moderate fine and medium subangular blocky structure; slightly hard, friable, slightly sticky and slightly plastic; common fine and medium, and few coarse roots; common very fine, fine and medium irregular and tubular pores; 10 percent gravel; very strongly acid (pH 4.8); clear smooth boundary. (0 to 11 inches thick)
Bt1--24 to 34 inches; brown (7.5YR 4/4) clay, brown (7.5YR 5/4) dry; moderate medium and coarse subangular blocky structure; hard, firm, moderately sticky and moderately plastic; few medium roots; common very fine and fine tubular pores; many distinct clay films on peds and lining pores; 5 percent gravel; very strongly acid (pH 4.6); gradual smooth boundary.
Bt2--34 to 54 inches; brown (7.5YR 4/4) clay, strong brown (7.5YR 4/6) dry; moderate medium and coarse subangular blocky structure; hard, firm, very sticky and very plastic; few fine roots; common very fine and fine tubular pores; many distinct clay films on peds and lining pores; 5 percent gravel; very strongly acid (pH 4.6); gradual smooth boundary. (Combined thickness of the Bt horizon is 22 to 51 inches)
BCt--54 to 60 inches; strong brown (7.5YR 4/6) silty clay loam, strong brown (7.5YR 5/6) dry; weak medium and coarse subangular blocky structure; hard, firm, sticky and plastic; few fine tubular pores; many distinct clay films on peds, lining pores, and coating rock fragments; 30 percent soft weathered siltstone gravel; very strongly acid (pH 4.6).
TYPE LOCATION: Douglas County, Oregon, about 4 miles northwest of Drain, 2,110 feet south and 790 feet west of the northeast corner of section 13, T. 21 S., R. 6 W. W.M. (Latitude 43 degrees, 44 minutes, 45 seconds N.; Longitude 123 degrees, 20 minutes, 56 seconds W.)
RANGE IN CHARACTERISTICS: Solum thickness is 30 to more than 60 inches. The soil is usually moist but is dry within the moisture control section for less than 45 consecutive days following the summer solstice. The mean annual soil temperature is about 47 to 55 degrees F. Hard rock fragments range from 0 to 15 percent and soft rock fragments range from 0 to 60 percent in the solum. Hue is 10YR or 7.5YR.
The A horizon has value of 2 to 4 moist, 3 to 6 dry and chroma of 2 to 4 moist and dry. It is silty clay loam, silt loam, gravelly loam, or gravelly silt loam. It has 0 to 30 percent gravel and 0 to 5 percent cobbles. It is very strongly acid to moderately acid.
The Bt horizon has value of 3 to 5 moist and 4 to 7 dry, and chroma of 4 to 6 moist and dry. It is clay, silty clay, silty clay loam, or clay loam with 35 to 45 percent clay and 0 to 15 percent gravel. It is very strongly acid or strongly acid.
The BC or C horizon, when present, has value of 4 to 6 moist and 5 to 7 dry, and chroma of 4 to 8 moist and dry. It is clay loam, clay, silty clay loam, silty clay, gravelly silty clay, gravelly clay loam with 30 to 45 percent clay and 0 to 30 percent gravel. There is up to 60 percent soft rock fragments in some pedons. It is very strongly acid or strongly acid.
COMPETING SERIES: These are the Cumley, Edson, Honeygrove, and McCurdy series. Cumley and McCurdy soils are moderately well drained. Edson soils have channer and flagstone shaped rock fragments. Honeygrove soils have Bt horizons with hue of 5YR or 2.5YR.
GEOGRAPHIC SETTING: Orford soils are on broad ridges, hill slopes, benches, and plateaus. They formed in colluvium and residuum derived from metasediments, metavolcanics, sandstone, siltstone, and volcanic tuffs. Slopes are 0 to 75 percent. Elevations are 100 to 3,500 feet. The climate is characterized by warm, wet winters and hot, moist summers. The mean annual temperature is 45 to 53 degrees F. The mean annual precipitation is typically 55 to 90 inches, but may range to 130 inches in the interior mountains of Curry County, Oregon. The frost-free period is 100 to 260 days.
GEOGRAPHICALLY ASSOCIATED SOILS: These are the competing Honeygrove series and the Blachly, Bohannon, Digger, Etelka, Gustin, McDuff, Peavine, Preacher, Remote, Rinearson, and Xanadu soils. Blachly and Xanadu soils have B horizons with hue of 5YR or 2.5YR. Bohannon, McDuff, and Peavine soils are moderately deep and are on convex positions. Digger soils are moderately deep and loamy-skeletal and are on convex or more steeply sloping positions. Etelka and Gustin soils are moderately well drained and are on concave positions. Preacher soils are fine-loamy. Remote soils are loamy-skeletal and are on convex or more steeply sloping positions. Rinearson soils are fine-silty.
DRAINAGE AND PERMEABILITY: Well drained; moderately slow permeability.
USE AND VEGETATION: Timber production, recreation, wildlife habitat, and water supply. A few areas are used for pasture. Native vegetation is Douglas fir, western hemlock, western redcedar, grand fir, tanoak, Pacific madrone with an understory of salal, Pacific rhododendron, evergreen huckleberry, western swordfern, cascade Oregongrape, Oregon oxalis, and red huckleberry.
DISTRIBUTION AND EXTENT: MLRA 1 and 3. The series is extensive.
MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: Portland, Oregon
SERIES ESTABLISHED: Curry County, Oregon, 1972.
REMARKS: Diagnostic horizons and features recognized in this pedon are:
Argillic horizon - from 24 to 60 inches. (Bt1, and Bt2, and BCt horizons)
Pale feature - the percentage of clay does not decrease from its maximum amount by 20 percent or more within a depth of 60 inches from the soil surface.
More than 0.9 percent organic carbon in the upper 6 inches of the Bt1 horizon based on laboratory data from Curry County, Oregon.
All diagnostic horizons and features are measured from the top of the first mineral horizon.
ADDITIONAL DATA: Laboratory data available for this soil. Reference sample S61OR-8-13-1 through 6 reported in Soil Survey Curry County, Oregon, January 1970, Oregon State University data.